-
-
Notifications
You must be signed in to change notification settings - Fork 2.4k
/
Base64OutputStream.java
183 lines (171 loc) · 6.62 KB
/
Base64OutputStream.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.fsck.k9.mail.filter;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Provides Base64 encoding and decoding in a streaming fashion (unlimited size).
* When encoding the default lineLength is 76 characters and the default
* lineEnding is CRLF, but these can be overridden by using the appropriate
* constructor.
* <p>
* The default behaviour of the Base64OutputStream is to ENCODE, whereas the
* default behaviour of the Base64InputStream is to DECODE. But this behaviour
* can be overridden by using a different constructor.
* </p><p>
* This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
* </p>
*
* @author Apache Software Foundation
* @version $Id $
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
* @since 1.0-dev
*/
public class Base64OutputStream extends FilterOutputStream {
private final boolean doEncode;
private final Base64 base64;
private final byte[] singleByte = new byte[1];
/**
* Creates a Base64OutputStream such that all data written is Base64-encoded
* to the original provided OutputStream.
*
* @param out OutputStream to wrap.
*/
public Base64OutputStream(OutputStream out) {
this(out, true);
}
/**
* Creates a Base64OutputStream such that all data written is either
* Base64-encoded or Base64-decoded to the original provided OutputStream.
*
* @param out OutputStream to wrap.
* @param doEncode true if we should encode all data written to us,
* false if we should decode.
*/
public Base64OutputStream(OutputStream out, boolean doEncode) {
super(out);
this.doEncode = doEncode;
this.base64 = new Base64();
}
/**
* Creates a Base64OutputStream such that all data written is either
* Base64-encoded or Base64-decoded to the original provided OutputStream.
*
* @param out OutputStream to wrap.
* @param doEncode true if we should encode all data written to us,
* false if we should decode.
* @param lineLength If doEncode is true, each line of encoded
* data will contain lineLength characters.
* If lineLength <=0, the encoded data is not divided into lines.
* If doEncode is false, lineLength is ignored.
* @param lineSeparator If doEncode is true, each line of encoded
* data will be terminated with this byte sequence (e.g. \r\n).
* If lineLength <= 0, the lineSeparator is not used.
* If doEncode is false lineSeparator is ignored.
*/
public Base64OutputStream(OutputStream out, boolean doEncode, int lineLength, byte[] lineSeparator) {
super(out);
this.doEncode = doEncode;
this.base64 = new Base64(lineLength, lineSeparator);
}
/**
* Writes the specified <code>byte</code> to this output stream.
*/
@Override
public void write(int i) throws IOException {
singleByte[0] = (byte) i;
write(singleByte, 0, 1);
}
/**
* Writes <code>len</code> bytes from the specified
* <code>b</code> array starting at <code>offset</code> to
* this output stream.
*
* @param b source byte array
* @param offset where to start reading the bytes
* @param len maximum number of bytes to write
*
* @throws IOException if an I/O error occurs.
* @throws NullPointerException if the byte array parameter is null
* @throws IndexOutOfBoundsException if offset, len or buffer size are invalid
*/
@Override
public void write(byte b[], int offset, int len) throws IOException {
if (b == null) {
throw new NullPointerException();
} else if (offset < 0 || len < 0 || offset + len < 0) {
throw new IndexOutOfBoundsException();
} else if (offset > b.length || offset + len > b.length) {
throw new IndexOutOfBoundsException();
} else if (len > 0) {
if (doEncode) {
base64.encode(b, offset, len);
} else {
base64.decode(b, offset, len);
}
flush(false);
}
}
/**
* Flushes this output stream and forces any buffered output bytes
* to be written out to the stream. If propagate is true, the wrapped
* stream will also be flushed.
*
* @param propagate boolean flag to indicate whether the wrapped
* OutputStream should also be flushed.
* @throws IOException if an I/O error occurs.
*/
private void flush(boolean propagate) throws IOException {
int avail = base64.avail();
if (avail > 0) {
byte[] buf = new byte[avail];
int c = base64.readResults(buf, 0, avail);
if (c > 0) {
out.write(buf, 0, c);
}
}
if (propagate) {
out.flush();
}
}
/**
* Flushes this output stream and forces any buffered output bytes
* to be written out to the stream.
*
* @throws IOException if an I/O error occurs.
*/
@Override
public void flush() throws IOException {
flush(true);
}
/**
* Closes this output stream, flushing any remaining bytes that must be encoded. The
* underlying stream is flushed but not closed.
*/
@Override
public void close() throws IOException {
// Notify encoder of EOF (-1).
if (doEncode) {
base64.encode(singleByte, 0, -1);
} else {
base64.decode(singleByte, 0, -1);
}
flush();
}
}